International efforts to end the conflict in Syria accelerate on Monday with key talks in Brussels and Paris, amid a push for a new peace conference despite growing divisions within the Syrian opposition.
US Secretary of State John Kerry will meet his Russian and French counterparts in Paris to advance an initiative for an international conference on ending the more than two-year conflict.
However Syria's main opposition group ended a fourth day of talks in Istanbul on Sunday with little sign of a joint approach to the attempt to bring all sides to the negotiating table.
The talks have been dubbed "Geneva 2" after a conference last June that produced a peace roadmap which failed to win support, triggering the resignation of Kofi Annan as special Syria envoy.
Ahead of the Paris meeting, the 27 EU foreign ministers meet in Brussels, with the bloc deeply divided over whether to arm the rebels.
After months of bitter argument, the issue will come to a head as the ministers meet ahead of the expiry at midnight on Friday of far-reaching EU sanctions against President Bashar al-Assad's regime including a weapons embargo.
Britain and France are leading the push to have the arms embargo maintained against Assad but relaxed against the Syrian opposition.
But British-based charity Oxfam has warned that allowing more weapons into Syria "could have devastating consequences" and "fan the flames of the conflict".
The latest peace push comes as Syria's leading opposition group was in total disarray at fractious talks in Istanbul, with discussions on their participation in the US-Russian peace initiative stalled.
There was squabbling over a vote early on Monday on expanding the opposition umbrella group, although the results formalised the entry into the Syrian National Coalition of veteran dissident and Marxist intellectual Michel Kilo.
Although the secular Kilo would bring in several women and members of Syria's religious minorities, critics said his entry would curb the Muslim Brotherhood's influence and force Saudi control on the coalition.
Syrian Foreign Minister Walid Muallem upped the ante on Sunday, saying his government would attend a new Geneva conference, terming it a "good opportunity for a political solution".
With the conflict spreading, Muallem said his government had agreed "in principle" to attend the conference.
The opposition's long-standing position is that, after more than two years of devastation which activists say has killed more than 94,000 people, it will not negotiate until Assad quits.
Recognised by dozens of states and organisations as the legitimate representative of the Syrian people, the opposition Coalition is marred by divisions that some members blame on regional bids for influence.
Forging a united position on Geneva is all the more urgent given rebel military setbacks on the ground, with regime forces reinforced by fighters from Lebanon's Shiite militant group Hezbollah.
Two rockets hit Hezbollah's heartland in the southern suburbs of Beirut on Sunday as its fighters battled alongside Syrian regime forces for control of the strategic town of Qusayr just across the border in central Homs province.
UN leader Ban Ki-moon said he was "deeply concerned" by Hezbollah's growing role in Syria and called for greater efforts to halt the spread of the conflict.
Hezbollah's chief Hassan Nasrallah said on Saturday it was in the militant anti-Israeli group's own interest to defend Assad's regime.
"I have always promised you a victory and now I pledge to you a new one" in Syria, he said.
Hours later, the two rockets slammed into Beirut, wounding four Syrians, in the first time the Lebanese capital's mainly Shiite southern suburbs have been targeted during the Syria conflict.
During the past week, 31 people have also been killed in clashes in Lebanon's northern port of Tripoli between Assad supporters and opponents.
Hezbollah's intervention has given Assad the upper hand in Qusayr, a key town in central Syria for both the regime and the insurgents.
It is an important rebel supply line from Lebanon but also links Damascus to Assad's Alawite coastal heartland.
Syrian forces mounted an offensive on Qusayr a week ago but are meeting fierce resistance.
On Sunday a source close to Hezbollah said regime forces had taken control of 80 percent of the town.